A liquid crystal display device is a device configured to display an image on a display surface thereof in such a manner that transmission/non-transmission in a liquid crystal layer for light radiated from a backlight unit is controlled based on an electric field to be applied to the liquid crystal layer.
Japanese Patent Application Laid-open No. 2009-48178 discloses a liquid crystal display device in which a black matrix is formed on a color filter in a non-display region surrounding a display region. Japanese Patent Application Laid-open No. 2013-37364 discloses a liquid crystal display device in which a light blocking pattern formed by laminating color filter patterns is formed in a non-display region surrounding a display region.
FIG. 8 is a cross-sectional view illustrating an exemplary structure of a conventional-art liquid crystal display device 50. The liquid crystal display device 50 is a display device that performs display with an IPS (in-plane switching) mode. The liquid crystal display device 50 includes a color filter substrate 510, a liquid crystal layer 520, a TFT substrate 530, a backlight unit 540, a seal member 550, and a frame 560.
The TFT substrate 530 includes a pixel electrode 531, a protective insulating film 532, a common electrode 533, a gate insulating film 534, a gate wiring layer 535, and TFT glass 536.
The color filter substrate 510 includes color filter glass 511, a light non-transmitting layer 512, and a planarization film 513. In the light non-transmitting layer 512, hole portions 517 are formed in a matrix, for example, which are filled with any one of three kinds of color resists 514, 515, and 516 corresponding to red, green, and blue, respectively.
In the liquid crystal display device 50, the transmission/non-transmission of light in the liquid crystal layer 520 is controlled based on an electric field in the horizontal direction of FIG. 8, which is generated by a potential difference between the pixel electrode 531 and the common electrode 533. Then, light from the backlight unit 540 passing through the liquid crystal layer 520 further passes through the color resist 514, 515, or 516, thereby displaying an image on a display surface.
In this case, when an image is displayed on the liquid crystal display device 50, a signal for operating a transistor for controlling a potential of the pixel electrode 531 propagates through gate wiring formed on the gate wiring layer 535. When a pulse signal is applied to the gate wiring, electric charges 600 generated by wiring coupling in the gate wiring propagate through the light non-transmitting layer 512 as indicated by the arrow of FIG. 8, and an electric field is generated between the electric charges 600 and the pixel electrode 531. As described above, in the liquid crystal display device 50, an image is displayed by controlling the transmission/non-transmission of light in the liquid crystal layer 520 based on the electric field formed between the pixel electrode 531 and the common electrode 533. When the electric field formed between the electric charges 600 and the pixel electrode 531 is applied to the liquid crystal layer 520, the molecular orientation of the liquid crystal layer 520 is changed, with the result that an unintended display of color (discoloration) may occur in the display image.
The present invention has been made in view of the above-mentioned problem, and it is an object thereof to provide a liquid crystal display device in which a display image is less affected by the electric charges 600 generated by wiring coupling.